In the case of agricultural harvesting machines, there is a need to acquire the throughput of crop gathered from the agricultural field in which it is harvested, in order, for example, to document it for accounting purposes or for applications in precision agriculture. The throughput is usually measured by baffle plates which are arranged next to the crop flow and give way against the force of a spring owing to the impacting crop flow. The position of the baffle plate depends on the mass throughput (that is to say the crop mass flow per unit time), and is acquired by means of a sensor whose signal indicative of the throughput is preferably recorded together with a reference to the geographical location where the throughput measurement was made.
In the case of combine harvesters, such baffle plates are usually arranged at the outlet of the grain elevator, which conveys the grain upwards before being cleaned, inside a transitional housing from which it is brought into the grain tank by means of a screw conveyor (see EP 0 208 025 A1). EP 1 305 994 A1 proposes fitting a capacitive moisture sensor directly below the baffle plate.
In addition, various spectroscopic measuring devices have been described in the prior art which are used in agriculture in order to classify crop material, for example. DE19922867A1 describes a spectroscopic measuring device for agricultural harvesting machines which comprises a light source for the purpose of irradiating the crop with light. Light reflected by the sample is deflected in a spectrometer by a dispersive element, for example a grating or a prism, in different directions dependent on the wavelength. Detector elements receive the light, now assigned known wavelengths, the wavelengths of which light lie in the visible wavelength region or in the near infrared region. The output signals of the detector elements are fed to an evaluation device which uses the measured spectra to calculate specific parameters and proportions of materials contained in the sample. The measuring device is located directly next to the crop flow on a discharge device of the harvesting machine, while the volume of the crop is acquired by a sensor which determines the distance between adjacent rollers (sensor rollers) between which the crop passes.
U.S. Pat. No. 5,751,421A1 and U.S. Pat. No. 5,092,819A1 describe combine harvesters having a measuring device for spectroscopic examination or acquisition of materials contained in the crop, which are arranged at the outlet of the grain elevator and cooperate there with the crop.
In the case of the measuring devices according to U.S. Pat. No. 5,751,421A1 and U.S. Pat. No. 5,092,819A1, no continuous acquisition of the crop throughput is provided, and the measuring arrangements described in EP0208025A1 and EP1305994A1 permit no spectroscopic examination of the crop, the measuring arrangement in accordance with DE19922867A1 is subject to the disadvantage that there is a time offset between the acquisition of the throughput at the sensor and the spectroscopic examination of the same crop. The assignment of the spectra to the throughput measured values is therefore problematic and would require a precise acquisition of the current conveying speed through the harvesting machine in addition to a high computational outlay.
It is an object of this invention to provide a measuring arrangement for spectroscopic examination and throughput acquisition of a crop flow which enables in a simple way an improved temporal correlation between the acquisition of the throughput measured values and the recording of the spectra of the same crop.
This object is achieved in accordance with the invention by the teaching of claim 1 herein. Additional related features of the invention are set forth in the further patent claims which further develop the solution.